1. Field of the Invention
The present invention relates to an inkjet recording device and an inkjet recording method.
2. Description of the Related Art
As printing methods that form printed images on printing media on the basis of image data signals, there are electrophotographic techniques, sublimation-type and fusion-type thermal transfer techniques, inkjet techniques and the like. An electrophotographic technique requires a process for forming a static electricity latent image, by static charging and exposure of a photosensitive drum. A system therefor is complex, and an apparatus is expensive. With a thermal transfer technique, an apparatus is inexpensive but, because ink ribbons are used, running costs are high and waste is produced. In contrast, with an inkjet technique, direct printing is carried out on a recording medium at an inexpensive apparatus by discharging ink only at required imaging sections. Consequently, colorants can be utilized with high efficiency and running costs are inexpensive.
As printing technologies which employ inkjet techniques, there are, for example, a method which retains and transports a recording medium on a drum (see Japanese Patent Application Publication (JP-B) No. 48-8005), a method which nips and transports a recording medium at a capstan roller (see Japanese Patent Application Laid-Open (JP-A) No. 2001-171103), a method which retains and transports a recording medium on an endless belt (see JP-A Nos. 2-238948, 2001-199071 and 2002-103598) and the like. Of these, the method with transport of a recording medium using an endless belt is effective when printing is to be carried out at high speed. In particular, high-speed printing is made possible by matching up a recording medium with a fixed-type full-line head having a printing length the same as the width of the recording medium. However, when an endless belt is employed, width direction meandering of the belt causes deterioration in image quality. Accordingly, an improvement in which relative positions of a plurality of rollers around which the belt is stretched are altered to vary tension at two ends of the endless belt, forms of the rollers are optimized, and restoring force is applied to return the endless belt to its original position when the endless belt meanders is well known. However, in this case, high precision control is necessary when carrying out high-speed printing with high definition, which is technically difficult. Furthermore, when a full-line head is employed, the number of nozzles is large, head problems due to blockages of the nozzles, breakdowns and the like occur, and images deteriorate. In a case in which non-discharging nozzles occur, which is particularly difficult to rectify, replacement of the head itself is necessary, and productivity of the printing system is reduced to zero until replacement is complete.
The present invention has been devised in order to solve the problems described above, and an object of the present invention is to provide an inkjet recording device and inkjet recording method capable of forming high quality images using a simple structure.
An inkjet recording device of a first aspect of the present invention for achieving the object described above is a structure which includes: an image-forming component which discharges ink for forming an image on a recording medium; a transport belt which has the form of an endless belt and which retains the recording medium at a predetermined position and transports the recording medium in a longitudinal direction; a position detection component which detects at least one of a relative position of the endless belt with respect to the image-forming component in a width direction and a relative position of the recording medium with respect to the image-forming component; and an alteration component which changes a position of image formation by the image-forming component in accordance with the at least one detected relative position.
The image-forming component of the present invention discharges ink and forms an image on a recording medium. The image recording is carried out while the recording medium is conveyed in the longitudinal direction of the transport belt by this endless-type transport belt. Here, there is a possibility that discharge of the ink will not be carried out at proper positions when the transport belt is displaced from a predetermined position of the belt in the width direction. Accordingly, at least one of the relative position of the endless belt in the width direction relative to the image-forming component and the relative position of the recording medium relative to the image-forming component is detected by the position detection component. Hence, the position of image formation by the image-forming component is altered by the alteration component in accordance with the detected relative position.
A high quality image can be formed more simply by varying the position of image formation by the image-forming component as described above than in a case of carrying out positional control of the transport belt by altering tension of the transport belt itself so that a restoring force acts on the transport belt.
An inkjet recording device of a second aspect is a structure which includes: an image-forming component which includes a plurality of nozzles and which utilizes electrostatic fields based on image data signals to discharge oil-based ink from the plurality of nozzles for forming an image on a recording medium; and an interpolation processing component which, in a case in which defects in discharge of the ink occur at a portion of the plurality of nozzles, carries out interpolation processing such that image formation is carried out by other nozzles instead of the nozzles affected by the defects, the other nozzles being properly working nozzles.
The image-forming component of the present invention discharges ink from the plurality of nozzles and forms an image on a recording medium. Here, in the case in which defects in discharge of the ink occur at some of the plurality of nozzles, a portion of image formation corresponding to those nozzles is not properly formed, and a deterioration of the image is caused. Accordingly, in the case in which the defects in discharge of the ink at some of the plurality of nozzles occur, interpolation processing is implemented by the interpolation processing component such that image formation is carried out by other, properly working nozzles instead of those nozzles. Here, defects in discharge of the ink can mean failures to discharge ink, abnormalities in discharge amounts, and/or abnormalities in discharge directions.
According to the structure described above, because the interpolation processing component interpolates the image formation portion corresponding to the nozzles affected by the ink discharge defects, deterioration of formed images can be prevented without the nozzles themselves being replaced.
An inkjet recording device of a third aspect is a structure including: an image-forming component which forms an image on a recording medium by utilizing electrostatic fields to discharge oil-based ink on the basis of image data signals; a recording medium transport component which includes a belt form and an endless form and which retains and transports the recording medium; a position detection component which detects a position, in a width direction of the recording medium transport component, of at least one of the recording medium transport component and the recording medium which is retained at the recording medium transport component; and a position control component which controls a position of the image-forming component in the width direction of the recording medium transport component on the basis of the position detected by the position detection component.
According to the structure described above, the position of the image-forming component is controlled by the position control component on the basis of the position of the at least one of the recording medium transport component and the recording medium. Thus, a high quality image can be formed more simply than in a case of altering tension of the transport belt itself and applying restoring force to the transport belt to carry out positional control of the transport belt.
In this inkjet recording device, the image-forming component may include a plurality of nozzles disposed in a direction substantially intersecting a direction of transport of the recording medium, and image formation by this plurality of nozzles is carried out by main scanning in the direction of transport of the recording medium. Here, the direction substantially intersecting the direction of transport of the recording medium is a direction on a surface of the recording medium that substantially intersects the direction of transport of the recording medium.
Further, in this inkjet recording device, the plurality of nozzles may be disposed spanning from one end to another end of an image formation region in a sub-scanning direction. According to this structure, image formation can be carried out over the whole of the sub-scanning direction of the image formation region by a single cycle of main scanning, and image formation can be carried out rapidly.
Further still, the inkjet recording device may further include a discharge defect nozzle detection component which detects discharge defect nozzles, which are nozzles among the plurality of nozzles that have discharge defects, and the position control component may move the image-forming component such that image formation is carried out by properly working nozzles, which are free of discharge defects, instead of the discharge defect nozzles detected by the discharge defect nozzle detection component.
Hence, because it is possible to form images with the properly working nozzles instead of the discharge defect nozzles, deterioration of images that are formed can be prevented without replacing the nozzles themselves.
In this inkjet recording device, retention of the recording medium to the recording medium transport component may be implemented by an electrostatic component.
Further, in this inkjet recording device, the recording medium that is retained at the recording medium transport component may be peeled off by one or both of an electrostatic component and a mechanical component.
Further still, in this inkjet recording device, the oil-based ink may be an ink in which at least colored particles are dispersed in a non-aqueous solvent with a characteristic electrical resistivity value of at least 109 xcexa9xc2x7cm and a relative dielectric coefficient of at most 3.5.
The inkjet recording device may further include an ink recovery component which recovers the oil-based ink from the image-forming component, and an ink supply component which supplies the oil-based ink that has been recovered by the ink recovery component to the image-forming component.
The inkjet recording device may further include a fixing component, which fixes the oil-based ink that has been discharged onto the recording medium.
A recording method using an inkjet recording device, of a fourth aspect of the present invention, includes the steps of: forming an image on a recording medium by discharging ink using an image-forming component; transporting the recording medium in a longitudinal direction of a transport belt, having retained the recording medium at a predetermined position of the transport belt; detecting at least one of a relative position of the transport belt relative to the image-forming component in a direction which intersects the longitudinal direction and a relative position of the recording medium relative to the image-forming component; and altering a position of image formation by the image-forming component in accordance with the detected relative position.
A recording method using an inkjet recording device, of a fifth aspect of the present invention, includes the steps of: forming an image on a recording medium by discharging oil-based ink from a plurality of nozzles using an electrostatic field on the basis of image data signals; and, in a case in which an ink discharge defect occurs at one or more of the plurality of nozzles, carrying out interpolation processing so as to substitute image formation by the nozzle at which the ink discharge defect has occurred with image formation by another of the nozzles.
A recording method using an inkjet recording device, of a sixth aspect of the present invention, includes the steps of: forming an image on a recording medium with an image-forming component by discharging oil-based ink using an electrostatic field on the basis of image data signals; transporting the recording medium in a longitudinal direction of a recording medium transport component, having retained the recording medium; detecting a position, in a direction intersecting the longitudinal direction of the recording medium transport component, of at least one of the recording medium transport component and the recording medium retained at the recording medium transport component; and, on the basis of the detected position, controlling a position of the image-forming component in the direction intersecting the longitudinal direction of the recording medium transport component.
As is described above, according to the inkjet recording device of the present invention, printed matter with clear, high quality images can be printed at high speed by a simple method. Further, an inkjet recording device can be provided which is reliable and whose productivity is not reduced to zero even when problems occur at a portion of nozzles at a head and that portion includes a large number of the nozzles.
Further still, according to the present invention, it is possible to print printed materials from different image information with clarity, low cost and high speed.